​​​​The European Space Agency has given its approval to technology developed by a British firm which could transform space travel – and lead to the development of an airliner capable of taking 300 passengers from Europe to Australia in four hours.

The Skylon aircraft is still at the theoretical stage, but the government is funding its development.

Reaction Engines Ltd, based in Oxfordshire, has developed a new type of jet engine, known as Sabre (Synergistic Air-Breathing Rocket Engine), which they say could power the space plane. The company has not yet built a full version of the engine, but it has constructed a critical component.

The heat exchanger made by Reaction is the key to the new technology, says The Independent. It cools air from 1,000C to 150C in one hundredth of a second, allowing the engine to use air as fuel, rather than oxygen from a tank.

Existing space rockets must carry tanks of oxygen with them – and the weight slows everything down. Reaction believe their new technology could make space travel 95 per cent cheaper.

The latest development is that the ESA have looked at Reaction’s data and agreed that the heat exchange technology is viable and workable. The next stage is to build working prototype of the full Sabre engine.

Last year, says the Daily Mail, the government announced it was investing £60m in building just such a prototype.

The Sabre technology could make space travel much cheaper and easier, allowing a jet aircraft to carry satellites and other spacecraft beyond the earth’s atmosphere before returning to the planet below. It could also be used to transport passengers quickly between distant locations on earth.

Reaction have designed an aircraft, the Skylon, which would use Sabre engines to carry 300 passengers from Europe to Australia within four hours. They hope to launch it as soon as 2019.